Lunar surface mobility in one-sixth gravity
How it felt to move and work on the Moon — the first human data on locomotion in one-sixth gravity, drawn almost entirely from the crew’s own account in the Technical Crew Debriefing (§10). Where the planning documents say what the crew would do, this is what the body actually did out on the surface during the EVA.
Adaptation was fast and easy. Both crewmen found 1/6 g “very natural” and adapted almost immediately — enough that they recommended not pursuing 1/6-g training exhaustively. Subjectively the gravity felt closer to one-tenth than one-sixth; objects were easier to handle than expected, though their mass and inertia persisted — “when they get going in a direction, they will keep going that way,” so things had to be handled deliberately.
The natural gait was a “lope.” Walking gave way to a lope — both feet briefly off the ground at once — as soon as the crew sped up (“I don’t think there is such a thing as running… you break into this lope”). The “kangaroo hop” worked but offered no advantage over putting one foot in front of the other. Balance was not difficult, but there was a tendency to tip over backward on a high jump; leaning slightly forward of the absolute neutral point was more comfortable, and the crew found they stayed “well-rooted” enough to make vigorous sideways motions without bouncing off the surface. Starting, stopping, or changing direction took two or three steps.
Traction, footing, and fatigue. Footing was generally good, but it was degraded by the clinging, “graphite-like” dust (which made rocks slippery) and by a soft top layer over a harder substrate of variable depth, which gave “a low confidence level in our balance and footing.” The 1/6-g aircraft (KC-135) was judged a poor simulator — it has too much traction to reproduce how the foot departs and lands. Loping was comfortable but tiring: Armstrong made the farthest traverse, ~200–300 ft to a 70–80-ft crater, and after ~500 ft of loping “was ready to slow down and rest”; a one-mile trek “was not going to be an easy thing,” and the crew judged that walking-return distances are limited — “it isn’t miles.” On the Moon one had to watch four or five steps ahead rather than one or two.
Specific limits. Getting down to the surface was hard — the suit was not cleared for routine kneeling, so retrieving dropped items or working at ground level “restricted us more than we’d like” (a held scoop or tool made it easy to push back up). At the other extreme, the crew could jump well: on ingress Armstrong sprang from a deep knee-bend to the third ladder rung, ~5–6 ft up. These observations fed directly into planning for later surface stays and for surface vehicles, which “isn’t going to be just any vehicle” given the Moon’s slopes, holes, and ridges.
The crew’s own Pilots’ Report (§4.12) independently describes the same rapid adaptation and the natural loping gait of one-sixth gravity.
Related
Section titled “Related”- Apollo 11 EVA (first moonwalk)
- Apollo 11 EVA life-support and mobility equipment
- Lunar regolith and soil mechanics
- Tranquility Base (Landing Site 2)
- LROC imaging of the Apollo 11 landing site